To investigate the role of bile acids (BAs) in the pathogenesis of diet-induced nonalcoholic steatohepatitis (NASH), we fed a “Western-style diet” [high fructose, high fat (HFF)] enriched with fructose, cholesterol, and saturated fat for 10 wk to juvenile Iberian pigs. We also supplemented probiotics with in vitro BA deconjugating activity to evaluate their potential therapeutic effect in NASH. Liver lipid and function, cytokines, and hormones were analyzed using commercially available kits. Metabolites, BAs, and fatty acids were measured by liquid chromatography-mass spectrometry. Histology and gene and protein expression analyses were performed using standard protocols. HFF-fed pigs developed NASH, cholestasis, and impaired enterohepatic Farnesoid-X receptor (FXR)-fibroblast growth factor 19 (FGF19) signaling in the absence of obesity and insulin resistance. Choline depletion in HFF livers was associated with decreased lipoprotein and cholesterol in serum and an increase of choline-containing phospholipids in colon contents and trimethylamine- N-oxide in the liver. Additionally, gut dysbiosis and hyperplasia increased with the severity of NASH, and were correlated with increased colonic levels of choline metabolites and secondary BAs. Supplementation of probiotics in the HFF diet enhanced NASH, inhibited hepatic autophagy, increased excretion of taurine and choline, and decreased gut microbial diversity. In conclusion, dysregulation of BA homeostasis was associated with injury and choline depletion in the liver, as well as increased biliary secretion, gut metabolism and excretion of choline-based phospholipids. Choline depletion limited lipoprotein synthesis, resulting in hepatic steatosis, whereas secondary BAs and choline-containing phospholipids in colon may have promoted dysbiosis, hyperplasia, and trimethylamine synthesis, causing further damage to the liver. NEW & NOTEWORTHY Impaired Farnesoid-X receptor (FXR)-fibroblast growth factor 19 (FGF19) signaling and cholestasis has been described in nonalcoholic fatty liver disease (NAFLD) patients. However, therapeutic interventions with FXR agonists have produced contradictory results. In a swine model of pediatric nonalcoholic steatohepatitis (NASH), we show that the uncoupling of intestinal FXR-FGF19 signaling and a decrease in FGF19 levels are associated with a choline-deficient phenotype of NASH and increased choline excretion in the gut, with the subsequent dysbiosis, colonic hyperplasia, and accumulation of trimethylamine- N-oxide in the liver.

Human-wildlife encounters are becoming increasingly frequent across the globe, often leading people to interact with and feed wild animals and impacting animal behaviour and ecology. Although the nature of human-wildlife interactions has been well documented across a number of species, we still have limited understanding as to why some individual animals interact more frequently with humans than others. Additionally, we lack a comprehensive understanding of how these interactions influence animal social networks. Using behavioural data from a group of moor macaque monkeys (Macaca maura), we used permutation-based linear regression analyses to understand how life history and social network factors jointly explain interindividual variation in tendency to interact with humans along a provincial road in South Sulawesi, Indonesia. As our study group spent only a portion of their time in proximity to humans, we also examined how social network structure changes in response to human presence by comparing social networks in the forest to those along the road. We found that sex, individual network position, and associate network position interact in complex ways to influence individual behaviour. Individual variation in tendency to be along the road caused social networks to become less cohesive when in proximity to humans. This study demonstrates that nuanced intragroup analyses are necessary to fully understand and address conservation issues relating to human-wildlife interactions.

The objective of this study was to investigate whether juvenile Iberian pigs with diet-induced non-alcoholic fatty liver disease (NAFLD), cholestasis and gut dysbiosis would develop histological and metabolic markers of neurodegeneration in the frontal cortex (FC), and whether supplementing probiotics would influence the response to the diet. Twenty-eight juvenile Iberian pigs were fed for 10 weeks either a control (CON) or high-fructose high-fat diet (HFF) with or without a commercial probiotic mixture. Compared with CON, HFF-fed pigs had decreased number of neurons and an increase in reactive astrocytes in FC tissue. We found also a decrease in one-carbon metabolites choline and betaine, and a marked accumulation of bile acids, cholesteryl esters, and polyol-pathway intermediates in FC of HFF-fed pigs, which were associated with markers of neurodegeneration and accentuated with the severity of NAFLD. Betaine depletion in FC tissue was negatively correlated with choline-derived phospholipids in colon content, whereas primary conjugated bile acids in FC were associated with cholestasis. Plasma kynurenine-to-tryptophan quotient, as a marker of indoleamine 2,3-dioxygenase activity, and intestinal dysbiosis were also correlated with neuronal loss and astrogliosis. Recognition memory test, and FC levels of amyloid β and phosphorylated Tau did not differ between diets, while probiotics increased amyloid β and memory loss in HFF-fed pigs. In conclusion, our results show evidence of neurodegeneration in FC of juvenile Iberian pigs, and establish a novel pediatric model to investigate the role of gut-liver-brain axis in diet-induced NAFLD.

The objective of this study was to investigate the effect of dietary fatty acid (FA) composition on bile acid (BA) metabolism in a pig model of NAFLD, by using a multiomics approach combined with histology and serum biochemistry. Thirty 20-d-old Iberian pigs pair-housed in pens were randomly assigned to receive 1 of 3 hypercaloric diets for 10 weeks: 1) lard-enriched (LAR; n=5 pens), 2) olive oil-enriched (OLI, n=5), and 3) coconut oil-enriched (COC; n=5). Animals were euthanized on week 10 after blood sampling, and liver, colon and distal ileum (DI) were collected for histology, metabolomics, and transcriptomics. Data were analyzed by multivariate and univariate statistics. Compared with OLI and LAR, COC increased primary and secondary BAs in liver, plasma and colon. In addition, both COC and OLI reduced circulating fibroblast growth factor 19, increased hepatic necrosis, composite lesion score, and liver enzymes in serum, and upregulated genes involved in hepatocyte proliferation and DNA repair. The severity of liver disease in COC and OLI pigs was associated with increased levels of phosphatidylcholines, medium-chain triacylglycerides, trimethylamine-N-oxide, and long-chain acylcarnitines in the liver, and the expression of pro-fibrotic markers in DI, but not with changes in the composition or size of BA pool. In conclusion, our results indicate a role of dietary FAs in the regulation of BA metabolism and progression of NAFLD. Interventions that aim to modify the composition of dietary FAs, rather than to regulate BA metabolism or signaling, may be more effective in the treatment of NAFLD.

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